Model Forum / Radio Controlled / Land Models / July 2003

Hello, everyone.  While on travel to the west coast recently I purchased a
miniature, 49 MHz RC U.S. Army tank model.  The unit was assembled in
China and appears to use the same technology as those "MicroSizer" cars
with a short wire serving as an antenna on the vehicle.  The model has a
quick (45 second) charge NiCd battery pack that is charged from the
control unit.

For a while the vehicle performed as expected until one of the two motors
(similar to the "MicroSnap" type but with leads) seized up.  I was able to
temporarily extract the motor and noticed that while it would make a
clicking sound when energized, the shaft failed to turn.  I rotated the
shaft by hand until it became free and then the motor started running.  I
reseated the motor in the tank and although it has continued to perform,
this motor consistently runs at a slower rpm than the other motor.  As a
result, when the tank is supposed to be travelling in a straight line it
instead describes an ellipse.  There appears to be nothing amiss with the
nylon gearing arrangement that drives the rubber tread.  I don't know what
might have happened to the motor but any comment is appreciated.
Sincerely,

John Wood (Code 5550)        e-mail: wood@itd.nrl.navy.mil                    
Naval Research Laboratory
4555 Overlook Avenue, SW
Washington, DC 20375-5337